Experimental study of near-wall transport and structures in turbulent Rayleigh-Bénard convection

固体与周围流体之间的热传递是许多自然流动和技术流动的主要过程。这个物理过程是在所谓的伊尔曼瑙桶中进行实验研究的，这是一个大型的瑞利-贝纳德实验，高8米，直径7米。由于普朗特尔对对流换热进行了研究，因此众所周知，对流换热系数\in (Q＿k = \alpha A \Delta T) （Q＿k—对流热流密度，A—面积，\Delta T—固体与流体之间的温差）取决于靠近固体表面的局部速度场。该速度场的表征是DFG研究小组FOR 1182实际项目RB-1的中心目标。利用三维激光多普勒测速、单点温度和速度同步测量以及2D2C粒子图像测速对平面速度场的测量，我们发现加热（冷却）表面附近的速度场非常复杂，具有很强的三维性。因此，全面的表征需要体积速度测量。

The heat transfer between a solid body and a surrounding fluid is a major process in many natural and technical flows. This physical process is studied experimentally in the so-called Barrel of Ilmenau - a large-scale Rayleigh-Benard experiment with a height of eight Meters and a diameter of seven Meters. Since Ludwig Prandtls work on the convective heat transfer, it is well known that the convective heat transfer coeffialpha cient \in the relation Q_k=\alpha A \Delta T (Q_k - convective heat flux, A - area, \Delta T - temperature difference between the solid body and the fluid) depends on the local velocity field adjacent to the surface of the solid body. The characterization of this velocity field is the central objective in the actual project RB-1 within the DFG Research group FOR 1182. Using 3d Laser Doppler velocimetry, simultaneous temperature and velocity measurements at single points and measurements of the planar velocity field using 2D2C Particle Image velocimetry, we found that the velocity field adjacent to the heated (cooled) surface is extremely complex and strongly three-dimensional. Hence, a comprehensive characterization requires a volumetric velocity measurement.